2 Answers
2

I think the thing you are looking for is "escrow" as in http://en.wikipedia.org/wiki/Key_escrow.
Be aware though that the security of your system is reduced to the hardness for an attacker to find the master password which might be much easier than breaking the disk encryption scheme

A good solution would be to hold the master password encrypted by a N+P sharing scheme, where a certain amount of perhaps board members, or third parties, would need to come together to be able to reconstruct the master password. c++ cryptopp does secret sharing (http://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing) through http://www.cryptopp.com/docs/ref/class_secret_sharing.html